Grids - DataController: Extract scrolling knowledge to extenders

[bit-byte0]

What

Moves the scrolling option knowledge out of the base grid DataController paging logic into the virtual scrolling module, so the base data layer no longer depends on scrolling

How

Base paging now delegates the paginate and total-count decisions to overridable resolvePaginate and requiresTotalCount hooks, and the scrolling option reset to optionChanged, which the virtual scrolling extender implements using its own scrolling-mode predicates

[Copilot]

🟡 Changes recommended

The newly added test’s ExposedDataController extends DataController redeclares protected members as public, which can cause a TypeScript inheritance error and break compilation.

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Pull request overview

This PR refactors grid paging logic so the base DataController no longer depends on scrolling options, delegating paging and total-count decisions to overridable hooks implemented by the virtual scrolling extender.

Changes:

• Added resolvePaginate() and requiresTotalCount() hooks to DataController and routed paging decisions through them.
• Moved scrolling-specific paging/total-count behavior into the virtual scrolling data controller extender (including handling scrolling option changes).
• Updated unit tests by removing resolvePaginate utility coverage and adding extender-focused paging tests.

File summaries

File	Description
packages/devextreme/js/__internal/grids/grid_core/virtual_scrolling/extenders/virtual_scrolling_data_controller.ts	Implements paging/total-count hook overrides and handles scrolling option changes within the virtual scrolling extender.
packages/devextreme/js/__internal/grids/grid_core/virtual_scrolling/extenders/tests/virtual_scrolling_data_controller.paging.test.ts	Adds new Jest coverage for virtual scrolling’s paging/total-count hook behavior and scrolling option reset behavior.
packages/devextreme/js/__internal/grids/grid_core/data_controller/utils/paging.ts	Removes resolvePaginate utility to keep paging utils independent of scrolling knowledge.
packages/devextreme/js/__internal/grids/grid_core/data_controller/utils/tests/paging.test.ts	Drops tests for the removed resolvePaginate utility, leaving syncPaging coverage.
packages/devextreme/js/__internal/grids/grid_core/data_controller/data_controller.ts	Removes scrolling handling from optionChanged and introduces overridable paging/total-count hooks used by base paging logic.

Review details

• Files reviewed: 5/5 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🔵 Needs a closer look

The newly added Jest test introduces a TypeScript type/visibility mismatch (widening protected hooks to public) that can break compilation.

Review details

Suppressed comments (1)

packages/devextreme/js/__internal/grids/grid_core/virtual_scrolling/extenders/tests/virtual_scrolling_data_controller.paging.test.ts:16

• The test declares ExposedDataController extends DataController and makes resolvePaginate/requiresTotalCount public, but those hooks are protected on DataController. TypeScript will treat this as an invalid inheritance (visibility widening) and can fail compilation for the test.

declare class ExposedDataController extends DataController {
  public resolvePaginate(enabled: boolean | undefined): boolean | undefined;

  public requiresTotalCount(): boolean;
}

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Lite